None.
Not Applicable.
This invention relates to a tensioning tool used with a tension band and clip system in spinal applications. The tensioning tool assists in the placement of the tension band and its corresponding clip. Once positioned, the tensioning tool pulls on the tension band through the clip and holds it while the clip is locked securely with the clip screw.
Surgical procedures for the repair or fusion of large and small bones, ligaments and tendons, and other orthopedic procedures frequently require use of an orthotic device or attachment apparatus which can be subject to tensioning and bear heavy loads caused by the unique anatomical features of the compromised bone or tendon. For example, fractures of the patella are exposed to high stresses during flexion and extension of the knee joint; fusions of the spinal vertebrae are exposed to high gravitational forces and movements of the spinal column; torn ligaments and tendons are exposed to high stresses due to contraction of the associated muscle or flexion and extension of the bony structures; and trochanteric reattachment and cerclage techniques involve cable that is tensioned and exposed to high weight loads and stress factors.
Examples of surgical cable attachments include U.S. Pat. No. 4,966,600 to Songer et al. Clamps for holding the cables are shown in U.S. Pat. No. 6,053,921 to Wagner et al. A polyethylene cable system is described in U.S. Pat. No. 5,456,722 to McLeod et al. Polyethylene cable tying is shown in U.S. Pat. No. 5,628,756 to Barker Jr., et al.
The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is xe2x80x9cprior artxe2x80x9d with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 C.F.R. xc2xa71.56(a) exists.
The invention provides a tensioning tool for use with a clip designed to grip and hold a tension band or cable without the use of any additional securing features such as knots, such as the clip shown and described in U.S. Provisional Patent Application No. 60/242,841 filed Oct. 24, 2000, the disclosure of which is incorporated by reference. It is especially well suited for use with braided polymeric cable. It employs a tapered screw concept which is customized using radii at both the root and crest of the thread. This prevents cutting of the cable. Standard clip designs using sharp teeth would cut individual cable strands leading to cable failure.
The clip design allows for easy engagement (starting of the thread) with progressively more compression of the braided cable. The female thread of the outer body is designed with a large radius where the cable exits to form a loop. The thread profile follows the main taper and thus blends gradually to zero depth. This, along with the large exit radius, minimizes all sharp bends which act to cut the cable under cyclic loading.
The tensioning tool is used with a clip through which the tension band ends are placed after the tension band is positioned over the body parts, such as adjacent spinous processes. The ends of the tension band are secured to pins on the tool and a tension shaft of the tool is driven downwardly away from the pins, increasing the distance from the pins to the clip, thereby tightening the bands. Once tightened as desired, a tension wrench is inserted through the tool with a clip screw positioned on its tip. It is then rotated until the screw is firmly seated in the clip, thereby trapping the band in between the clip and screw. The tool is then removed after releasing the band ends from the pins. Any excess band ends may be trimmed away.